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Abstract

Vertical malocclusions develop as a result of the interaction of many different etiological factors; one of the most important of these factors is mandibular growth. Variations in growth intensity, function of the soft tissues and the jaw musculature as well as the individual dentoalveolar development further influence the evolution of these malocclusions. This article reviews the most common etiological factors and their possible contribution to the development of vertical malocclusions with special emphasis on the role of mandibular growth in the development of open bite and deep bite. The role of the cephalometric morphological analysis in the differential diagnosis of vertical malocclusion is emphasized. Aspects of orthodontic treatment of vertical malocclusions are illustrated with individual cases.

Abstract

The informative value of clinical material presented at meetings and in the literature poses a dilemma for the typical orthodontist. To aid in the resolution of this problem, methodological aspects of the following topics are discussed: criteria for the evaluation of orthodontic treatment results, the selection of cases to be evaluated, the presentation of orthodontic treatment results and the interpretation of case presentations. Orthodontic relapse should be considered to be a number of continuous variables affecting treatment results; different follow-up criteria should be employed when comparing pretreatment, posttreatment and postretention results.

Abstract

The purpose of this study was to compare short-term (approximately 12 months postoperatively) and long-term (24 to 81 months postoperatively) records of 36 patients who underwent superior repositioning of the maxilla via LeFort I osteotomies. The parameters of measurement were set up to analyze the net response of the soft tissues of the face to superior repositioning of the maxilla. The results of this study show that soft-tissue changes associated with maxillary impaction are minimal and that no significant differences exist between twelve-month records and five-year records.

Abstract

Integrated electromyographic activity of masseter and anterior temporal muscles was recorded using bipolar surface electrodes in 33 young adults. Subjects were skeletally classified according to ANB angle reading corrected both for maxillary position and rotation of the jaw.

Postural activity for both muscles was higher in Class III subjects than in Class I and Class II, whereas in Class I and II subjects activity was similar. During swallowing, masseter muscle activity in Class III subjects was higher than Classes I and II, whereas anterior temporal muscle activity was not different between Classes III and I. During maximal voluntary clenching, activity was not different among classes. High correlations between electromyographic activity and corrected ANB angle as well as with overjet were observed.

Skeletal classification used in the present study may have clinical relevance regarding treatment and prognosis, as well as in the assessment of the relationship between muscular activity and craniofacial characteristics.

Abstract

The present study was designed to investigate the nature of friction between orthodontic wire and various ceramic brackets. The amount of tooth movement with metal and ceramic brackets was measured, and the wire surfaces were examined microscopically immediately after artificial tooth movement.

The amount of tooth movement produced by the ceramic brackets was significantly less than that produced by metal bracket. The wire surfaces were scratched more obviously by ceramic brackets than by metal bracket. Slot surfaces and edges of the ceramic brackets were substantially more porous and rougher than those surfaces of the metal bracket.

These material differences between metal and ceramic brackets significantly affect the efficiency of orthodontic tooth movement.

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Abstract

Coefficients of friction were evaluated in the dry and wet (saliva) states for stainless steel, cobalt-chromium, nickel titanium, and beta-titanium wires against either stainless steel or polycrystalline alumina brackets. For both operators' experiments, an 0.010″ stainless steel ligature wire pressed each archwire into the 0.018″ or 0.022″ bracket slot at 34°C.

In the dry state and regardless of slot size, the mean kinetic coefficients of friction were smallest for the all-stainless steel combinations (0.14) and largest for the beta-titanium wire combinations (0.46). The coefficients of the polycrystalline alumina combinations were generally greater than the corresponding combinations that included stainless steel brackets. In the wet state, the kinetic coefficients of the all-stainless steel combinations increased up to 0.05 over the dry state. In contrast, all beta-titanium wire combinations in the wet state decreased to 50% of the values in the dry state. The mixed reports that saliva may promote adhesive and lubricious behaviors may have some substance.

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